Optical MR Coil Tracking for PET Attenuation Correction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In combined PET and MR systems, MR hardware, particularly local coils, attenuate PET emissions, leading to inaccurate attenuation correction due to unknown positioning and deformation, resulting in up to 10% errors in PET activity concentration.

Innovation Solution

Use optical cameras to capture images of MR hardware on the patient, determine its position and deformation, and generate an attenuation coefficient map to correct for MR hardware attenuation in PET imaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If MR local coils are placed close to the patient surface for MR imaging, then MR image quality is improved, but PET attenuation correction accuracy deteriorates due to unknown coil positioning and deformation

Engineering Contradiction:

ImproveMR signal reception qualityVSAvoidPET attenuation correction accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

Optical fiducial markers are introduced as intermediaries between the MR coil and the imaging systems. These markers are attached to known locations on the coil and are visible to both optical cameras and MR systems, enabling the determination of coil position and orientation without interfering with MR signal reception or PET photon detection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical tracking of the MR coil with an optical measurement system. Optical cameras capture images of fiducial markers on the coil, and image processing algorithms determine the coil's 3D position and orientation, substituting complex mechanical tracking mechanisms with a simpler optical approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If flexible local coils are used to conform to patient body, then MR imaging coverage is improved, but PET attenuation correction becomes impossible due to unknown coil deformation

Engineering Contradiction:

ImproveCoil conformability to patient bodyVSAvoidPET activity concentration accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Optical fiducial markers serve as intermediaries that maintain known geometric relationships on the flexible coil. Even when the coil deforms to conform to the patient's body, the relative positions of these markers remain predictable, allowing optical systems to determine the coil's deformed state and calculate appropriate attenuation corrections

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs color-coded markers with distinct visual characteristics that are easily distinguishable by optical cameras. These markers may have different colors, patterns, or reflectivity properties that facilitate automatic detection and identification, enabling accurate determination of coil position and orientation even when the coil is deformed

Inventive Principle:

Principle #32Color changes

3Adaptability or versatility

If MR hardware is used for PET/MR combined imaging, then imaging versatility is improved, but PET photon detection is attenuated by MR coil and housing materials

Engineering Contradiction:

ImproveCombined PET and MR imaging capabilityVSAvoidPET photon intensity

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system performs preliminary optical imaging to determine the position and orientation of MR hardware before PET data acquisition. An attenuation coefficient map is generated in advance based on the detected coil position, allowing the PET reconstruction algorithm to pre-compensate for expected photon attenuation, thereby recovering signal intensity that would otherwise be lost

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Accurately accounts for MR hardware attenuation, improving PET imaging accuracy by reducing errors in activity concentration.

Implementation Method 1

An optical camera images the patient. The imaging captures an image of the patient and the MR hardware.

Methodology Applied

Scientific EffectOptical imaging: Photography

Implementation Method 2

the coil and coil-housing materials attenuate the 511 keV photons that are emitted from the patient and used to create the PET image

Methodology Applied

Scientific EffectPhoton attenuation: Absorption (EM radiation)

Data Source

PatentUS12387393B2Magnetic resonance hardware-contributed attenuation in positron emission tomography

Publication Date: 2025.08.12 SIEMENS MEDICAL SOLUTIONS USA INC

AI summary

PET imaging (406) accounts for attenuation by MR hardware (110). A camera (112) captures the MR hardware (110) as positioned on or by the patient (116). For example, MR local coils to be or as positioned between the emission sources in the patient (116) and the PET detector are optically imaged (402). Image processing is used to determine (404) the position of the MR hardware (110). The attenuation of the MR hardware (110) is accounted for in attenuation correction for PET imaging (402) based on the determined position.